Combined vibratory scrubber, stratifier, and screen for minerals



@Ci- 29, 1946- W. L. zElGLl-:R ET AL 2,410,326

COMBINED VI/BRATORY SCBUBBER, STRATIFIER, AND SCREEN FOR MINERALS FiledNov. 12, 1943 7'2 sheets-sheet .1

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Oct. 29, 1946. W. L ZEIGLER ET A1.

COMBINED VIBRATORY SCRUBBER, STRATIFIER, AND SCREEN FOR MINERALS FiledNov. 12, 1943 2 sheets-sheet 2 Snoentor WLLLLAM Lamm-ER c; LAL/Ds Y.GARBBR Patented Oct. 29, 1946 -COI^YBINED VIBlXtA'IQRY SCR'UBBER, STRAT--IFKER, AND SCREEN-FOR MINERALS lWilliam L. Zeiglen'Wallace, and ClaudeY. Garbei', Kellogg, Idaho, assignors to The 'Sink & Float-Corporation,New York, N. Y., a corpora- Application November 12, 1943, Serial No.509,982

3 Claims. l

This invention relates to a combined vibratory scrubber, stratierandscreen for minerals useful in mineral particle treatment processes, and,more particularly, to a method of screening .ore particles and astepped-pool Washing screen for treating such multi-size mineralparticles for screening and desliming or decolloiding of the material orfor .the separation and sorting of extraneous materials that maytherewith be included.

.In the `art of mineral separation, a common practice is to Vgrind orein the presence of water to reduce its size to particles that maybetreated by sink and float, jigging, tablingor other related processes.Objects of grinding-are theliberation of mineral particles, sizing forsubsequent treatment, and to meet commercial requirements in an endproduct. .It appears to loe-an inescapable result of Wet grinding thatthere is createdslimes or colloidal materials to the detriment Aof thesubsequent `treating processes. In the -case of crushed materials .slimecoatings will make the material untreatable and reduce the eiciencyofthe sink and float steps.

It has been our observation that when crushed ore contaminated-withslimes or colloids is .passed to conventional screens for removal vofthe lines from the coarser particles the Whole volume Atends toagglomerate linto a mass in which `the slimes are plastered in agel-like state upon the particles to thereafter travel with them intosubsequent sink and iioat or recovery steps to the detriment of theselater operations. Such occurs rather than the more desirable screening,desliming or decolloiding which we have found possible vto perform witha maximum output ,of clean valuable material at high speed and in `greatvolume by the use of our invention more'fully described herein.

Another diiculty that is encountered in screening and deslimingoperation arises from ascarcity of water for use in spraying thematerial to eliminate the colloids or slimes. This clifliculty isparticularly prevalent in the desert mining districts, as are common-inCalifornia, where the .amount of Water that may be apportioned todesliming must be cut to the absolute minimum since slime is not readilydewatered or thickened.

In the art of mineral recovery all of the problems mentioned above arefocused into one large problem making for real trouble vin .the Imillingoperations. For example, it appears to be common for minerals whenground to be accompanied bylarge quantities of fines, slimes and...colloids which must be removed if `a Asink and oat recovery is to beeconomically practical or even possible. The prior treatments ofminerals, therefore, according to conventional practices of screeningand desliming, require large volumes of water to produce satisfactoryresults. It appears to be a quirk of nature rthat minerals must be foundin dry areas where such quantities of Water are not always available foruse in the crushing and-sorting stages of the milling operations.

A fairly recent innovation in the more modern mills has been theadoption and use of vibratory screens for medium, coarse and finesorting. In such devices a rapid and low amplitude `positive vibrationis imparted lto move the screens in Various horizontal, oblique orvertical motions, with or without the screen being supported trulyhorizontal. Such vibrations are employed to produce screening as well asforward feed of the material. These screens are recognized as havinggood volume but, as we have learned in our wide experience in mineralrecovery, are accompanied by the problem mentioned above ofagglomeration of the fines, slimes and colloids with the minerals in ahighly detrimental manner by altering in an undesirable Way the specificgravity and viscosity of the sink and float medium as well as throughthe tendencies of the slimes to contaminate the medium and consequentimpairment of the sink and floatprocess. In all cases, even where watersupply is no problem, high velocity spraying does not result/infill] orsatisfactory screening or desliming.

`Having in mind the'defects of the v prior lart of screening, it is anobject of our invention to .provide a method .and means of handlingparticle materials in a manner to produce accurate separations orsorting in great capacity with a marked delineation between variousproducts of the feed mass. Y

Another object of our invention is to provide a sorting screen .andoperating means therefor .that will fully perform the steps of ourmethod vof particleseparation without including the prior art defects ofsuch similar mechanisms.

Still another obiect .of this invention .is the :provision, in a sortingscreen of .the type mentioned, of a stratifying and scrubbing .poolwhich will rapidly and accurately .produce separation of mixed andmulti-size particles in any of several desired. manners, while alsopreventing or breaking up agglomeration.

A still further Yand more specific object ofthis invention is .theprovision .of a vibratory tscreen having stepped pools in 'sequence forvparticle treatment in a series of stages at a high volume feed withoutslime contamination of those particles most sought by those leastsought.

The foregoing objects and others ancillary thereto we prefer toaccomplish as follows:

According to a preferred embodiment of our method of particleseparation, we feed crushed ore or similar granular material into a poolof nuid that is under the effect of reciprocatory or gyratory vibration.During such cycles of vibration the material is subjected to themechanical forces in the presence of the water in a pool and withoutscreening and is then passed across a screen for sorting and theelimination of certain of the mixture therethrough and the passageforward of that which does not go through the screen. In the specificembodiment of the invention shown here, we arrange that these steps beperformed in repetition several times for subsequent retreatment eitherto variously grade the material into several sizes or to repeatedlysubject the material to the same action for the elimination of onecontent from the remainder of the feed mass. In the former case, screenshaving varying characteristics are included in the sequence while in thelatter case the screens are identical so that al1 the undersizedmaterial is the same and the coarse will be uniform and merely have beenrepeatedly retreated. The screens are supported in incline so that awedge shaped pool may be created with the pointed end directed with thefeed of the material.

That portion of the screen plate forming the bottom of the pool isimperforate while that portion that lies under the tapering end of thepool and forward thereof is perforate for the downward passage ofparticles that are to leave the mass along with a portion of the uid.Water or other fluid supply means are provided to flood the same into apool in low pressure slow velocity streams. Likewise material feed meansare employed for supplying material to the rear end of the pool in aconstant manner. The screen is supported in its preferred angularity ina frame that is in turn resiliently supported upon springs so that it isfree to move under the effect of a shaker mechanism 'associatedtherewith for that purpose. In the case of a desliming operation whereinthe slime passing through .the screen tends to stick to and travel alongthe underside of the screen throughout its length means are provided fordamrning such flow and for directing that material downward away fromthe screen and to free it from the mechanism. In certain instances a dammay be provided across the upper face of the screen to retardstratification and fluid movement in a forward direction to meetconditions sometimes encountered wherein it is desirable to lengthen theperiod that the particles are inthe fluid pool.

The novel features that we consider characteristics of our invention asset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and the method of itsoperation, together with additional objects and advantages thereof, willbest be understood from the following description of a specificembodiment when read in connection with the accompanying drawings, inwhich Figure 1 is a longitudinal vertical sectional view of a vibratoryscreen that performs our method and embodies our invention,

A Figure 2 is an enlarged view of a portion of the screens of Figure 1,

Figure 3 is a plan view of the frame and its screens,

Figure 4 is a vertical sectional view on the plane suggested by lines 44 of Figure 1,

Figure 5 is a perspective View of a portion of a screen,

Figure 6 is an enlarged fragmentary sectional view of a portion 0f thescreen and the dam used thereon, and

Figure 7 is a fragmentary View in cross section showing the manner ofapplying the method to the ordinary fiat screen,

A separation method and means for use herein to overcome the defectshereinbefore enumerated must have at least two totally distinctcharacteristics; th'e method must be capable of performance with a highcapacity output coupled with high efficiency of separation of variousparticles in the feed material; and the mechanism must be capable, in aconstant manner, of performing the process with a maximum of efficiencyand a minimum of wear under hard usage. Accordingly, a preferredembodiment of my invention, referring .to Figure 1 of the drawings, isconstituted by a resiliently supported frame which has as the principalbottom member thereof a perforate and imperforate screening plate. Theframe comprises upright side Walls I0 and I2 joined at the feed end bywall I4 and at the tail end by wall I6 which is slotted at I8 for theoutward passage of tailing materials from the inside the frame. Near themiddle of the side walls a cross beam 20 is secured therebetween tostiffen the frame and to form a support for the shaker head 2I shown inFigure 1. This shaker head includes case 22 in which is journalled forrotation parallel shafts 24 and 2E to the former of which is secureddrive means to which power is supplied in a conventional manner toproduce rotation of shaft 24 and through gears 30, 3I to driven shaft26. Each of these shafts have unbalanced rotor members which operate tounbalance each other and create vibration.

The frame formed of walls I0, I2, I4 and I6 is spring suspended byresilient links 34 from suitable overhead supports 33 and, when thevibrator head 2l is attached and caused to operate, will receive fromsaid head vibration which causes .the frame and its screens to move ingyration preferably at an -angle oblique to the generally horizontalplane in which the frame is disposed.

Near the lower edges of the walls forming the frame in cups 35 ismounted a plurality of cross bars 36 which are shown to be cantedforward so that the upper forward edge of each overhangs the lower edgeon the forward face. The upper and lower faces of each bar 36 issubstantially horizontal. These bars form the primary supports for thesorting screens 38, 38a, 38h, 38e and 38d each of which have end flanges39 and 4i! that are inclined at an acute angle to the screen andoppositely to each other for engagement of the screen to adjacent bars36. The rear ange 39 is hooked over the lower edge of the rearmost bar36 of an adjacent pair and the forward flange 40 similarly engages overthe upper edge of the forwardmost bar of such a pair. The rear edge ofscreen 38 which is the first of the series is hooked under the flange ofanchor clip 42 mounted on the frame and is held there by the retainerbar 44 through the instrumentality of bolts d5. A spring leaf 4B pressesthe upper face of the screen 38. The most forward end of screen 38d, thelast in a series, is engaged by anchorA clip 48 and drawn taut by thebolt 50. Since the intermediate cross bars 36 are loosely seated in cups35 the whole serrated assembly is movable slightly under the urgence ofthe end anchor take-up means, `the screens may be tensioned to a degreeafter assembly.

I lEach of the screens comprises imperforate vportion A and perforateportion B as suggested walls of the frame, and the portion A -o'f eachscreen forms a wedge-shaped pocket which will contain fluid and materialduring operation of the machine. This fluid in the pool P is wedgeshapedsince it has an upper generally horizontal face which converges with therising bottom formed by the imperforate portion of the screen inltangentiality with the perforate portion B.

Beneath each screen on suitable cross bars 52 we mount resilient buffersupports 54 in contact with the under face of the screen.

On occasion a dam 55 is attached to the mid upper Space of the screen toalter the fluid level in the pool P and to retard feed material in thepool for purposes of stratification or to prolong the scrubbingtreatment in any one pool. These dams are preferably formed of rubberand are usually attached to the screen along the line of demarcationbetween the perforate and imperforate zones A and B.

Feed material is delivered to the left end of the screen as shown inFigure 1 by a conduit 58 having a discharge end 60. This material beinglargely fluid flows readilyonto and across the screen 38.

Water or other treating fluid is delivered to the screens through aprimary conduit 62 that runs longitudinally of the frame above thescreens and has several lateral headers 64 from which depend the spigots65. The incoming water is preferably not under a great head, it beingprimarily intended that it fiow freely under the natural effect ofgravity to discharge smoothly rather than jet-like as has previouslybeen conventional practice.

The method In practice our separation process comprising the treatmentof a fluid mass composed of liquid and solid particles to effect aseparation of a po-rtion of the particles from others thereof. As hasbeen said before, such separation can be desirable in selectiveseparation of several types or sizes of particles from a mass such assand and gravel or, as we have more particularly applied the invention,to the separation of slimes or colloids from oversize mineral particlesin mineral treatment processes. In either case the basic function of themethod is the same and comprises the imparting of vibration to a fluidmass but without permitting screening of the same during a scrubhing andstratification period and then, subsequently, screening and decanting aportion of the stratified mass to remo-ve a selected portion or stratumfrom the remainder. Therein lies an important distinction from priorconventional practices wherein screening takes place simultaneous withscrubbing and stratifying since by postponing the screening operationuntil adequate stratification takes place we facilitate the scrubbingand desliming (in the case of mineral separation) vand produce cleaneroverflow oversize than has .heretofore beenk possible.

By the use of low amplitude high frequency vibration during thestratifying period of our process we speed the layering effect withoutretardi-ng the capacity of our separation means because when separationtakes place the portion of the material to lbe separated from themassleaves -rapidly and without requiring prolonged screening as hasbeen necessitated before. An important phase of our method lies in theforming and maintenance of a pool of fluid containing particles ofvarious sizes and natures which pool is then vibrated to stratify andscrub the same and to intermittently separate, decant and advance aportion of the mass over the screen in its highly stratified conditionto permit the slimes, fines and fluid to drop out of the mass and awayfrom the individual particles passing on over the screen.

Operation of the appawtus With the screen resiliently suspended and theshaker head operating to vibrate the screen, fluid gangue is fed to thescreens near the left end as shown in Figure 1 lby the conduit 50 andadditional treating liquid is supplied near the pockets in the screenassembly through the spigots 66. The mass being treated forms a pool onthe lower rear end of screen 38, as well as on the others in the case ofa sequential series, and is there momentarily retained while it isvibrated whereby the particles in the mass are scrubbed against eachother in fluid and the walls of the pool to separate the slimes from thecoarser particles and the mass is stratified. During the cycles ofvibration of the mass a portion of the same is ad- Vanced up theinclined face of the screen from the imperforate zone A to the perforatezone B which permits the fines and slimes that have collected in thelowermost stratum as well as the fluid to drop through the openings inthe screen while the oversize particles pass on forward to the lip atthe upper corner of the support bar 36, whence it cascades into the nextpool and is similarly retreated either in repetition or for the nextlargel` sizing and sorting operation.

Such slimes and fluid as descend through the screen openings often tendto cling to the underside of the screen and produce blinding thereof orto travel forward in an undesirable underfeed following the contours ofthe screen until it is returned to the coarser mass to recontaminate it.To defeat this-action we employ the' dams comprising members 52 and 54which serve to supportV the screens from below. As the forwardlycreeping slime contacts the rear sideof the dam it is deflected downwardaway from the screen and is caused to fall away by the vibration ofthose members.

The dam 56 on the upper face of the screen may or may not be used, butwhen it is used it serves to retard forward movement of increments inthe pool P until proper stratification has taken place and the fiuidlevel has risen to permit an increment to pass over the apex of thedarn.

Although we have shown and described a certain specific embodiment ofour invention, we are fully aware that many modifications are possibleto meet slightly altered conditions. This we have in mind throughout ourdescription of our invention, which we claim as follows:

O-ur method and mechanism may be applied to existing flat top vibratingscreens by fastening bars 68 across the screen as shown in Figure 7 tomaintain liquid pools on the top of the screen plate or cloth. Thisapparatus consists of cross 'barsGBboth above and below the screen plateor cloth between which the screen is supported to maintain the liquid inthe pool. VThe perfora- `tions -in the screen or cloth are stopped olfby a suitable plate as Hi which may be clamped between the bars forsecure placement.

We claim:

'1. A vibratory separator, comprising: a serrated deck formed ofinclined plates having risers `between adjacent plates, each said platebeing forate and periorate portions to the apex, and

means for vibrating said deck longitudinally "thereof, whereby particlebearing fluid has the particles therein scrubbed and stratified andportions thereof intermittently decanted for the removal of a portion ofthe fluid and of particles of a size to pass through said screen.

2. A vibratom7 separator, comprising: a serrated deck formed of inclinedplates having risers ybetween adjacent plates, said risers being cantedforward, each said plate being perforate adjacent its apex andimperforate adjacent the root, said plates being characterized by beingsmooth from the root across the imperforate and perforate 4portions tothe apex, and means for vibrating said deck longitudinally thereof,whereby particle bearing fluid has the particles therein scrubbed andstratified and portions thereof intermittently decanted for the removalof a portion of the fluid and of particles of a size to pass throughsaid screen.

3.7A vibratory separator, comprising: a serrated deck formed of inclinedplates having risers between adjacent plates, each-said plate beingperforate adjacent its apex and imperforate adjacent the root, saidplates being characterized by being smooth from the root across theimperforate and perforate portions to the apex, and means for vibratingsaid deck longitudinally thereof, whereby particle bearing fluid has theparticles therein scrubbed and stratied and portions thereofintermittently decanted for the removal of a portion of the fluid and ofparticles of a size to pass through said screen, and defiectors incontact with the underside of said plates to prevent creeping of slimesand the like and to direct the same away from the screen.

WILLIAM L. ZEIGLER. CLAUDE Y. GARBER.

